any good resource for cafs and compressor information?

[firenoobie]

hey all,

thought this would be the best spot to put this. I need to do an engine placement/knowledge class for a crew and last shift failed the signoff because I was asked questions about the compressor and cafs system. I have a basic idea from what i found online about the cafs system but the manuals i found were pretty technical and hard to understand. I was wondering if anyone has a good link explaining some of the other uses of a compressor on a fire engine (if there are?) other then cafs, and if there is a good online resource about the compressor/cafs system. Thanks!

[chiefengineer11]

hey all,

thought this would be the best spot to put this. I need to do an engine placement/knowledge class for a crew and last shift failed the signoff because I was asked questions about the compressor and cafs system. I have a basic idea from what i found online about the cafs system but the manuals i found were pretty technical and hard to understand. I was wondering if anyone has a good link explaining some of the other uses of a compressor on a fire engine (if there are?) other then cafs, and if there is a good online resource about the compressor/cafs system. Thanks!

One other use for the compressor is that can be a source of compressed air for whatever you might need compressed air for. Examples would be airing up tires, air bags, etc.

Since the compressor that is used in many of the systems is essentially the same as what's used on construction contractors' compressors, it could also be an emergency source of a large flow of air. Remember that the truck engine air brake compressor produces in the range of 12 - 16 CFM of air at 120 psi. CAFS compressors are usually much higher. Ours will do 200 CFM at 125 psi and the pressure can go somewhat above that.

We have one 3" CAFS discharge on our engine that does not have a line preconnected to it. In the engineer's compartment are two 3" discharge caps that we made. One has a standard Milton "M" quick connect fitting that matches all of our in-station air lines and tools. The other has a standard contractor's connector that's used for jackhammers and the like. We haven't used the contractor's one yet, but it's there. Both were inexpensive to make and don't take up alot of space.

[TVFR9923]

It would help to know who the manufacturer of the system is.

[npfd801]

One other use for the compressor is that can be a source of compressed air for whatever you might need compressed air for. Examples would be airing up tires, air bags, etc.

Since the compressor that is used in many of the systems is essentially the same as what's used on construction contractors' compressors, it could also be an emergency source of a large flow of air. Remember that the truck engine air brake compressor produces in the range of 12 - 16 CFM of air at 120 psi. CAFS compressors are usually much higher. Ours will do 200 CFM at 125 psi and the pressure can go somewhat above that.

We have one 3" CAFS discharge on our engine that does not have a line preconnected to it. In the engineer's compartment are two 3" discharge caps that we made. One has a standard Milton "M" quick connect fitting that matches all of our in-station air lines and tools. The other has a standard contractor's connector that's used for jackhammers and the like. We haven't used the contractor's one yet, but it's there. Both were inexpensive to make and don't take up alot of space.

Sam - what's your SOG for keeping the compressor cool when you're operating it just for air? I'll freely admit my CAFS knowledge is weak at best, and the only unit I sold with CAFS was a PTO driven compressor unit from Darley. Always something new I should be learning...

[chiefengineer11]

Sam - what's your SOG for keeping the compressor cool when you're operating it just for air? I'll freely admit my CAFS knowledge is weak at best, and the only unit I sold with CAFS was a PTO driven compressor unit from Darley. Always something new I should be learning...

Quite simple, Joel: Open the tank to pump and crack open the tank fill.

Since we have the pump driven compressor, you have to have the pump running to power the compressor. So you obviously want water circulating. A portion of what you are pumping passes through the compressor oil cooler.

Something we learned after I got a call one Saturday morning about the CAFS oil temp going up too high - if you open the tank fill all the way, all of the water being circulated goes to to our 2" tank fill. The pressure is too low to force any through the cooler tube bundle. So we learned, only crack the tank fill enough to hear water flowing through it. And watch the oil temp gauge!

Chief Lou or Gregg Geske, anything to contribute, anything I missed?

[CaptLou]

Hi All,

Sam, you pretty much said it correctly. The only thing I would add is to make sure you keep an eye on the CAFS oil temperature gauge during air ONLY operations (even normal operations).

Remember the booster tank is acting like the radiator in your car, with regards to cooling. So on a hot August day and knowing that the average oil temperature is around 180 degrees, you could possibly heat saturate the water in the booster tank. Not to mention the fact that the churning of the fire pump generates heat as well. Which would require the dumping and re-filling with cool water if you need air for a prolonged period of time. Or simply be connected to a hydrant or other water source and just let the water overflow the booster tank.

Now the size of the booster tank, how much water is left in the booster tank, outside air temperature, how long and how hard the compressor is working will all play into the time frame it takes to heat saturate a booster tank. But you can run in the AIR ONLY mode for quite some time, an hour or so, give or take 15 minutes either way with 500 gallons of waters in a booster tank.

Also during a CAFS operation when you are flowing CAFS the heated water is being discharged out the fire hose.

Hope this helps.

Be safe.

Chief Lou
"Got Foam?"